JPH0760167B2 - Inverter main circuit Switching device quality judgment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention checks the quality of each main circuit switching element that constitutes an inverter, and determines whether the inverter main circuit switching element is good or bad. It relates to the device.

[Conventional technology]

FIG. 7 is a connection diagram showing a pass / fail judgment device for a conventional inverter main circuit switching element. In the figure, 8 is a main circuit switching element for one arm in the inverter, in which a transistor is used. Reference numeral 9 is an insulation resistance measuring device such as a tester or a megger connected between the collector and emitter of the main circuit switching element 8.

Next, the operation will be described.

If the main circuit switching element 8 is damaged for some reason and a short circuit accident occurs, the main circuit switching element 8 has a reduced insulation resistance and becomes conductive. Therefore, a large current flows through the insulation resistance measuring instrument 9, and the damage is detected and displayed.

[Problems to be Solved by the Invention]

Since the conventional pass / fail judgment device for the switching circuit of the main circuit of the inverter is configured as described above, the collector and the emitter must be separated from other circuit elements in a circuit manner and a check must be made for each element during the pass / fail judgment measurement. On the other hand, after the check, each collector and emitter must be reconnected to other circuit elements, which complicates the measurement work, prolongs the failure recovery time, and results in extremely poor measurement efficiency. there were. A technique similar to this device for determining the quality of an inverter main circuit switching element is described in a data book, "90 Mitsubishi Semiconductor, Power Module Edition" (published by Mitsubishi Electric Corporation).

The present invention has been made in order to solve the above problems, the presence or absence of a damaged main circuit switching element at the time of emergency recovery work of an accident can be promptly carried out for all used elements, It is an object of the present invention to obtain a device for determining the quality of an inverter main circuit switching element that can identify the main circuit switching element, if any.

[Means for Solving the Problems]

According to a first aspect of the present invention, there is provided an inverter main circuit switching element pass / fail judgment apparatus, in which two main circuit switching elements are connected in series for each phase between the inverter main circuit input terminals and the main circuit switching elements. Each element has a flywheel diode connected in parallel in the same direction, and an inverter output terminal having an output point at a connection point of each main circuit switching element for each phase, and at least one of the inverter output terminals and the other remaining Connect a DC power supply between the and, to supply a voltage for checking the insulation of each of the main circuit switching elements through the flywheel diode and the current limiting resistor, and through the current limiting resistor. The current flowing through each of the main circuit switching elements is detected by a current detector.

According to the second aspect of the present invention, there is provided an apparatus for determining the quality of an inverter main circuit switching element, which comprises two main circuit switching elements connected in series for each phase between the inverter main circuit input terminals, and the main circuit switching element. A flywheel diode connected in parallel for each element, an inverter output terminal having an output point at the connection point of each main circuit switching element for each phase, and connected between at least one of the inverter output terminals and the other The voltage for checking the insulation of each main circuit switching element is
An AC power supply that is supplied via the flywheel diode and the current limiting resistor, and a current detector that detects a current flowing through each of the main circuit switching elements via the current limiting resistor, and the current detector A comparator compares and determines whether or not the detected current value exceeds a set level, and according to the result of the comparison and determination, the main circuit switching element that has failed is identified and the display element is turned on.

[Action]

The DC power supply in the invention according to the first aspect applies a voltage for measurement to the main circuit switching element to be measured through the flywheel diode of the sound arm of a specific phase, and at this time, limits the current. By detecting the current flowing through the resistance for use by the current detector, the damage of the main circuit switching element can be detected by specifying each arm.

Further, the comparator in the invention according to the second claim compares the alternating current flowing at the time of failure of each main circuit switching element with the set level, and according to the comparison result,
When the current exceeds the set level, it functions to light the display element based on the output of the comparator.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, S _{U to} S _Z are main circuit switching elements (hereinafter referred to as elements) that constitute a three-phase inverter main circuit, and D _{U to} D _Z.
Is a flywheel diode for each arm, 1 is the above-mentioned three-phase inverter main circuit, 2 is an element pass / fail judgment device connected to this three-phase inverter main circuit 1, and 3 is a power supply which constitutes this element pass / fail judgment device 2. DC power supply, 3a, 3b are output terminals of the DC power supply 3, 4 is a current limiting resistor, 5 is a DC power supply 3
A switch connected between the current limiting resistor 4 and the current limiting resistor 4, 6 and 7 are current detectors, and an ammeter or the like is used. The DC power supply 3 is connected between at least one of the inverter output terminals and the remaining one through the current detectors 6 and 7 and the current limiting resistor 4. U, V, W are the output terminals of the inverter (hereinafter referred to as terminals).

Next, the operation will be described. Note that here, assuming that the element S _U of the upper arm of the U phase is damaged, the element S _U
Will be described with a circle in the figure. In this state, the switch 5
When a voltage is applied to the terminals U, V, W from the DC power supply 3 by closing the terminal, the terminal V becomes a positive potential, and this voltage is also applied to the element S _U via the flywheel diode D _V.
Now, if the element S _U is sound, it means that it has the ability to withstand the voltage E, and no current flows through the current detector 6. On the other hand, if the element S _U is damaged and short-circuited, assuming that the current limiting resistor 4 has a resistance value R, a current corresponding to about E / R flows to the current detector 6, and at this time, The current value is detected. At the same time, the voltage E of the DC power source 3 is also applied between the inverter output terminal V-W, W presence of elements S _W similarly damaged phase upper is to be detected by the current detector 7 . In the pass / fail judgment test of such elements S _U and S _W , the inverter main circuit input terminals P and N are opened, and at the same time, the elements S _{U of} each arm are
~ It is assumed that all S _Z trigger signals are off. As described above, the quality of the upper arm elements of the U and W phases can be determined.

On the other hand, the determination of the lower arm elements S _X , S _Z can be performed in the same manner by switching the polarity of the DC power supply 3 using the switch 10 as shown in FIG. The remaining elements S _V and S _Y of the upper and lower arms can be replaced by switching the DC power source 3 connected to the first V terminal to the U terminal or W terminal side after opening the switch 5. The quality can be determined in the same manner as above. Further, by making the DC power supply 3 a variable output voltage type, when a large current flows through the damaged element, the output voltage can be narrowed before opening / closing the switch 5 and the switch 5 can be opened / closed in the state of zero current. it can. In this case, if the DC power supply 3 has a current limiting function, the current limiting resistor 4 is not necessary.

FIG. 3 shows another embodiment of the element pass / fail judgment device 2, and FIG. 3 (a) omits the switch 5 and the current limiting resistor 4
Connect only one between current detectors 6, 7 and DC power supply 3,
It is used for both U and W phases. According to this, the configuration can be simplified and the cost can be reduced. Also,
Fig. 3 (b) shows a switch 5 added to Fig. 3 (a), and Fig. 3 (c) shows the switch 5 in Fig. 3 (b) for each of the U and W phases. The switches 5a and 5b are separately provided. In each of these circuits, the same functions and effects as in the above embodiment can be obtained.

In the above embodiment, the DC power supply 3 is switched and connected to the U phase or W phase when the quality of the elements S _V and S _Z of the upper and lower arms of the V phase is shown. You can also do it.

FIG. 4 shows another embodiment of the present invention. 1 is different from that shown in FIG. 1 in that the AC power supply 3A is connected to the V-phase terminal V instead of the DC power supply 3 as a power supply, and the AC power is supplied to the AC power supply 3A and the current detectors 6 and 7. The point is that an element pass / fail judgment indicator 11 is connected to judge and display a damaged element by receiving the signal 3a corresponding to the output and the detection signals 6a and 7a.

FIG. 5 is a circuit diagram showing a concrete example of the element quality judgment indicator 11 in FIG. 4, and 12a, 12b, 12c are the respective signals 3a, 6a, 7
Comparators for judging the level of a, 13a, 13b, 13c are output signals of these comparators 12a, 12b, 12c, 14a, 14b, 14c
Is an AND gate that takes the logical product of these output signals 13a, 13b, 13c, and 14d is the AND gate that takes the logical product of the signal 13d obtained by passing the output signal 13a through the inverter 15 and the output signal 13c, 15
Reference numerals a, 15b, 15c and 15d are flip-flops that latch the outputs of the AND gates 14a to 14d, and 16a, 16b, 16c and 16d are display elements such as lamps and light emitting diodes that indicate the presence or absence of element damage.

Next, the operation of the embodiment shown in FIGS. 4 and 5 will be described. Here, a case where the element S _U is damaged will be described as in the above-described embodiment.

First, the switch 5 is turned on, and the AC power supply 3A is applied between the output terminals U, V and W at the peak value E. As a result, assuming that the resistance value of the current limiting resistor 4 is R, the outputs of the current detectors 6 and 7 are equivalent to a current of about E / R peak value when there is a damaged element, as shown in FIG. Signal. Therefore, the voltage E between V and U
Element from the diode D _V but the positive polarity when, as shown in FIG. 6
A current flows through the current detector 6 through S _U, and the magnitude of this current is detected. At this time, no current flows in the current detector 7, and the signal 7a is zero as shown in FIG.

On the other hand, the detection signal 6a input to the element pass / fail judgment indicator 11
Is compared with the comparison level I _C by the comparator 12b, and the display element 16a is turned on as shown in FIG. 6 at the timing when the detection signal 6a exceeds the comparison level I _C. The lighting of the display device 16a is present and arm position with this broken element S _U of the damaged element S _U (for example, at the time of the upper arm of U-phase, the display element 16a is lit) it can be seen that instructs. Similarly, if the AC power source currently connected to the V phase is switched in connection with the U phase or the W phase, the quality of the upper and lower arm elements of the V phase can be similarly determined.

In this embodiment, each element of the upper and lower arms, for example, the element
If both S _R and S _Y are damaged, the quality of other phases cannot be judged, but it can be seen that the upper and lower arms of either phase are damaged at the same time. so,
In the case of FIG. 1, it is sufficient to disconnect either the U phase or the W phase and the element pass / fail judgment device 2 for re-judgment.

In this embodiment as well, the connection between the element quality determiner 2 and the terminals U, V, W of the inverter main circuit 1 is shown in a wire connection type. However, a changeover switch is provided to change the connection of the wire when the V phase is judged. Instead, it can be connected by the changeover switch.

Further, in the above embodiment, only four light emitting elements 16a to 16d are provided for each of the upper and lower arms of the two phases, but six light emitting elements are provided for all the arms and each light emitting element can be switched at the same time when the changeover switch is switched. You may do it.

〔The invention's effect〕

As described above, according to the first aspect of the present invention, two elements connected in series for each phase between the inverter main circuit input terminals and each element connected in parallel in the same direction. A flywheel diode and an inverter output terminal having an output point at a connection point of each element for each phase, and a DC power supply is connected between at least one of the inverter output terminals and the other, and each of the above The voltage for checking the insulation of the main circuit switching element is supplied via the flywheel diode and the current limiting resistor,
Since it is configured to detect the current flowing through each element through the current limiting resistor by the current detector, it is possible to detect the presence or absence of element damage and the damage site without disconnecting each element. It is possible to shorten the work time for accident recovery, and because the quality of each element is judged by measuring the current value, no skill is required, and it is possible to reliably judge and detect the quality of the element. effective.

According to the second aspect of the invention, the comparator determines whether or not the AC current value detected by the current detector exceeds a set level, and when the AC current value exceeds the set level. In addition, since the corresponding display element is turned on, there is an effect that it is possible to display whether or not the element is damaged and the damaged portion so that any person can identify it.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a device for judging quality of an inverter main circuit switching element according to an embodiment of the present invention, FIG. 2 is a connection diagram showing switches used in FIG. 1, and FIG.
FIG. 4 is a circuit diagram showing each embodiment of the element quality judgment device in FIG. 4, FIG. 4 is a device for judging quality of an inverter main circuit switching element showing another embodiment of the present invention, and FIG. Circuit diagram showing a specific configuration of the determination indicator,
FIG. 6 is a timing chart showing signals at various parts of the circuit shown in FIG. 5, and FIG. 7 is a circuit diagram showing a conventional pass / fail judgment device for an inverter main circuit switching element. P, N are input terminals of the inverter main circuit, S _U ~ S _Z are main circuit switching elements, D _U ~ D _Z are flywheel diodes, U,
V and W are inverter output terminals, 3 is a DC power supply, 3A is an AC power supply, 4 is a current limiting resistor, and 6 and 7 are current detectors. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. Two main circuit switching elements connected in series for each phase between inverter main circuit input terminals,
A flywheel diode connected in parallel for each main circuit switching element, an inverter output terminal whose output point is the connection point of each main circuit switching element for each phase, and insulation of each main circuit switching element. A DC power supply connected between the inverter output terminals of the two phases so as to supply a voltage for checking through the flywheel diode and the current limiting resistance, and each of the main terminals through the current limiting resistance. A pass / fail judgment device for an inverter main circuit switching element, comprising a current detector for detecting a current flowing through the circuit switching element. 2. Two main circuit switching elements connected in series for each phase between the inverter main circuit input terminals,
A flywheel diode connected in parallel for each main circuit switching element, an inverter output terminal whose output point is the connection point of each main circuit switching element for each phase, and insulation of each main circuit switching element. An AC power supply connected between the inverter output terminals of two phases so as to supply a voltage for checking through the flywheel diode and the current limiting resistor, and each of the main terminals through the current limiting resistor. A current detector that detects the current flowing in the circuit switching element, a comparator that compares and determines whether the current value detected by this current detector exceeds a set level, and the main circuit switching that has failed according to the output result of this comparator. Inverter main circuit switching element equipped with a display element that identifies and lights the element Determination device.